Disposable retainer



FIG. 1 is a perspective view of a disposable retainer showing the front and left sides of my new design;

FIG. 2 is a plan view thereof;

FIG. 3 is a front view thereof; and

FIG. 4 a rear view thereof; and,

FIG. 5 is left side elevational view.

The broken line depict portions of the disposable retainer that form no part of the claimed design. 

CLAIM The ornamental design for a disposable retainer, as shown and described. 